Resistance welding of sheet metal coated with layers

ABSTRACT

The invention relates to apparatus for the resistance welding of sheet metal panels coated with layers. In all of the disclosed forms of the invention electrical contact is established between the sheets and between the welding electrodes and the sheets, and welding is thereafter effected across the coating layers. Electrical contact is established in several ways, for example, by shunts connecting the electrodes to the coated panels; by auxiliary contacts in the form of pins electrically connecting the superposed panels; by filler welding pieces; by electrodes provided or associated with cutting means for penetrating the coating layer; by the use of press-in bodies which penetrate the coating layers, and by the use of heating means to melt or fuse the coating layer.

United States Patent Becker 1 1 July 29, 1975 [54] RESISTANCE WELDING OFSHEET METAL 3,277,268 l0/l966 Williams et a1. 219/92 3,337,711 8/1967Garscia 219/92 COATED WITH LAYERS [76] Inventor: Otto Alfred Becker. 59Robert- Koch-Strasse, 66, Saarbrucken, 6, Germany [22] Filed: Dec. 30,1970 [21] Appl. No.: 102,950

Related US. Application Data [62] Division of Ser. No. 704,684, Feb. 12,1968, Pat. No.

[30] Foreign Application Priority Data Feb. 11, 1967 Germany 91162 May26, 1967 Germany 92707 Apr. 24, 1967 Germany 92210 Feb. 27, 1967 Germany91404 [52] US. Cl. 219/92; 219/93; 219/94 [51] Int. Cl 823k 9/28; 823k11/10 [58] Field of Search 219/91, 92, 93, 94

[56] References Cited UNITED STATES PATENTS 3,231,710 1/1966 Barnet etal. 219/91 Primary Examiner-J. V. Truhe Assistant ExaminerHugh D. JaegerAttorney, Agent, 01' Firm-Erich M, H Radde [57] ABSTRACT The inventionrelates to apparatus for the resistance welding of sheet metal panelscoated with layers. In all of the disclosed forms of the inventionelectrical contact is established between the sheets and between thewelding electrodes and the sheets, and welding is thereafter effectedacross the coating layers. Electrical contact is established in severalways, for example, by shunts connecting the electrodes to the coatedpanels; by auxiliary contacts in the form of pins electricallyconnecting the superposed panels; by filler welding pieces; byelectrodes provided or associated with cutting means for penetrating thecoating layer; by the use of press-in bodies which penetrate the coatinglayers, and by the use of heating means to melt or fuse the coatinglayer.

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1. A device for resistance welding of insulation-coated sheet metal toat least one other coated sheet metal, said device comprising a firstmain electrode and, in juxtaposition thereto, a second main electrode,at least one first auxiliary electrode being arranged side-by-side ofsaid first main electrode and being electrically insulated therefrom, atleast one second auxiliary electrode being arranged side-by-side of saidsecond main electrode and being electrically insulated therefrom, saidfirst and second auxiliary electrodes being also in juxtaposition toeach other, means for moving at least one of said main electrodes andits adjacent auxiliary elEctrode toward and away from the other main andauxiliary electrodes so as to provide a space for placing superposedinsulation-coated sheet metal panels between said first and second mainand auxiliary electrodes, and to establish contact between said sheetmetal panels and said electrodes on moving the electrodes toward eachother, a shunt connecting the first main electrode with the secondauxiliary electrode and a shunt connecting the first auxiliary electrodewith the second main electrode, regulating resistor means provided insaid shunts, a welding current source, and connections from said weldingcurrent source to said main electrodes.
 2. The device of claim 1, inwhich a pair of juxtapositioned auxiliary electrodes is arranged on eachside of said pair of main electrodes.
 3. The device of claim 1, in whichthe auxiliary electrodes are constructed as welding tongs, the arms ofsaid tongs positioned at the side of the first main electrode andforming the first auxiliary electrode being isolated from the arms ofsaid tongs positioned at the side of the second main electrode andforming the second auxiliary electrode, said arms being electricallyinsulated from each other by insulating discs provided between said armsand an insulating axle of the tongs.
 4. A device for resistance weldingof insulation-coated sheet metal to at least one other coated sheetmetal, said device comprising a first main electrode and, injuxtaposition thereto, a second main electrode a first auxiliaryelectrode being arranged side-by-side of said first main electrode andbeing electrically insulated therefrom, a second auxiliary electrodebeing arranged side-by-side of said second main electrode and beingelectrically insulated therefrom, said first and second auxiliaryelectrodes being also in juxtaposition to each other, means for movingat least one of said main electrodes and its adjacent auxiliaryelectrode toward and away from the other main and auxiliary electrodesso as to provide a space for placing superposed insulation-coated sheetmetal panels between said first and second main and auxiliaryelectrodes, and to establish contact between said sheet metal panels andsaid electrodes on moving the electrodes toward each other, a shuntconnecting the first auxiliary electrode with the juxtapositioned secondauxiliary electrode, regulating resistor means provided in said shunt, awelding current source, and connection from said welding current sourceto said main electrodes.
 5. A device for resistance welding ofinsulation-coated sheet metal to at least one other coated sheet metal,said device comprising a first double-point electrode and, injuxtaposition thereto, a second double-point electrode, saiddouble-point electrodes comprising an electrode and a counter-electrodeof opposite polarity arranged in parallel side-by-side position to eachother, the electrodes and counter-electrodes of said juxtapositionedfirst and second double-point electrodes being positioned so that eachelectrode and counter-electrode on one side of the sheet metal panel isof opposite polarity to each electrode and counter-electrode on theother side of the sheet metal panel, means for moving at least one ofsaid double-point electrodes towards and away from the otherdouble-point electrode, so as to provide a space for placing superposedinsulation-coated sheet metal panels between said first and seconddouble-point electrodes and to establish contact between said sheetmetal panels and said double-point electrodes on moving the electrodestoward each other, a welding current source, and connections from saidwelding current source to said double-point electrodes.
 6. A device forresistance welding of insulation-coated sheet metal to at least oneother coated sheet metal, said device comprising two juxtapositionedwelding electrodes, means for moving at least one oF saidjuxtapositioned electrodes toward and away from the other electrode soas to provide a space for placing superposed insulation-coated sheetmetal panels between said electrodes and to establish contact betweensaid sheet metal panels and said electrodes on moving the electrodestoward each other, press-in wires placed between each electrode and thecontacting sheet metal, shunts connecting each press-in wire to theopposite electrode, a welding current source, and connections from saidwelding current source to said electrodes.
 7. The device of claim 6, inwhich the pressin wires are supported by a step-by-step movable holderbelt and in which the connections of the shunts with the pressin wiresare sliding contacts.
 8. A device for resistance welding ofinsulation-coated sheet metal to at least one other coated sheet metal,said device comprising two juxtapositioned welding electrodes, the onefirst electrode having an annular cutting edge on its tip, said annularcutting edge cutting through the coating layer and establishing contactwith the blank metal of the sheet metal, the other opposite secondelectrode being a swivel electrode, means for moving at least one ofsaid juxtapositioned electrodes toward and away from the other electrodeso as to provide a space for placing superposed insulation-coated sheetmetal panels between said electrodes and to establish contact betweensaid sheet metal panels and said electrodes on moving the electrodestoward each other, a shunt connecting said second electrode with thesheet metal contacted by the first electrode, a welding current source,and connections from said welding current source to said electrodes. 9.The device of claim 8 in which a protective hood is arranged around saidfirst electrode, said hood being adapted to rest on said sheet metalpanel, said hood being connected with a means for supplying a protectivegas and with an exhaust means for removing the protective gas.
 10. Adevice for resistance welding of insulation-coated sheet metal to atleast one other coated sheet metal, said device comprising twojuxtapositioned electrodes, means for moving at least one of saidelectrodes toward and away from the other electrode so as to provide aspace for placing superposed insulation-coated sheet metal panelsbetween said electrodes and to establish contact between said sheetmetal panels and said electrodes on moving the electrodes toward eachother, a clamping tong establishing a shunt from one surface of thesheet metal panel to the other surface of said panel, said clamping tonghaving contact cutter blades pivotally mounted on the jaws of saidclamping tong, said contact cutter blades pentrating the coating layersto establish contact with the blank metal of the sheet metal panels, awelding current source, and connections from said welding current sourceto said electrodes and said clamping tong.
 11. A device for resistancewelding of insulation-coated sheet metal to at least one other coatedsheet metal, said device comprising two juxtapositioned first and secondelectrodes, the first of said electrodes being provided with a centralbore and having mounted in said bore a spring-biased thrust pin adaptedto penetrate the coating layer of the adjacent sheet metal and toestablish contact of the first electrode with the blank metal of saidsheet metal, means for moving at least one of said electrodes toward andaway from the other electrode so as to provide a space for placingsuperposed insulation-coated sheet metal panels between said electrodesand to establish contact between said sheet metal panels and saidelectrodes on moving the electrodes toward each other, an auxiliarycontact means spaced from said electrodes and passing through the sheetmetal panels so as to electrically connect the metal sheets with eachother, a shunt connecting said auxiliary contAct means with the secondelectrode, a welding current source, and connections from said weldingcurrent source to said electrodes.
 12. A device for resistance weldingof insulation-coated sheet metal to at least one other coated sheetmetal, said device comprising two juxtapositioned welding rollerelectrodes for roller seam welding, said welding roller electrodescomprising two roller discs and interposed between them a cutter rollerdisc adapted to penetrate the coating layers of the metal sheetsadjacent the roller electrodes and thus to establish contact of theroller electrodes with the blank metal of said sheet metals, means formoving at least one of said electrodes toward and away from the otherelectrode so as to provide a space for placing superposedinsulation-coated sheet metal panels between said electrodes and toestablish contact between said sheet metal panels and said electrodes onmoving the electrodes toward each other, an auxiliary contact meansspaced from said electrodes and passing through the sheet metal panelsso as to electrically connect the metal sheets with each other, awelding current source, and connections from said welding current sourceto said electrodes.
 13. The device of claim 12, in which the cutterroller disc is mounted on resilient flanged sleeves giving way intoinner recesses of the welding rollers and a groove is provided on thecommon shaft of the welding rollers and the cutter roller disc.
 14. Adevice for resistance welding of insulation-coated sheet metal to atleast one other coated sheet metal, said device comprising twojuxtapositioned welding electrodes, means for moving at least one ofsaid electrodes toward and away from the other electrode so as toprovide a space for placing superposed insulation-coated sheet metalpanels between said electrodes and to establish contact between saidsheet metal panels and said electrodes on moving the electrodes towardeach other, contact press-in means interposed between each electrode andthe adjacent metal sheet of the sheet metal panel, said contact press-inmeans being pressed into and through the coating layers onto the blankmetal of said metal sheets on movement of the electrodes toward eachother and thus establishing contact between the electrodes and the blankmetal of the metal sheets, an auxiliary contact means spaced from saidelectrodes and passing through the sheet metal panel so as toelectrically connect the metal sheets with each other, a welding currentsource, and connections from said welding current source to saidelectrodes.
 15. The device of claim 14, in which the contact press-inmeans are supported by a step-by-step movable holder belt, said beltmoving between the electrodes and the adjacent metal sheet andautomatically supplying said contact press-in means to the spots to bewelded.
 16. A device for resistance welding of insulation-coated sheetmetal to at least one other coated sheet metal, said device comprisingtwo juxtapositioned welding electrodes, heating means provided at atleast one of said electrodes, said heating means being adapted to atleast soften the coating layer of the coated metal sheets adjacent tothe electrode, means for moving at least one of said electrodes towardand away from the other electrode so as to provide a space for placingsuperposed insulation-coated sheet metal panels between said electrodesand to establish contact between said sheet metal panels and saidelectrodes on moving the electrodes toward each other, said meanscausing displacement of the at least softened coating layer by thepressure of the electrodes moving towards each other, a welding currentsource, and connections from said welding current source to saidelectrodes.
 17. The device of claim 16, in which the heating means is atubular heating stamp guided on the electrode, said heating stamp beingheatable by heating coils and being spring-biased towards the sheetmetal panel.
 18. The device of claim 16, in which the heating means is abolt-shaped heating stamp guided in the electrode, said heating stampbeing heatable by heating coils and being spring-biased towards thesheet metal panel.
 19. The device of claim 16, in which the heatingmeans is an internal hot air device comprising a hot air supply pipe anda vent pipe being arranged in a central bore of the electrode.
 20. Thedevice of claim 16, in which the heating means is an outer heating meansarranged around the electrode, said heating means comprising a hot airheating tube guided slidably on the electrode, a biasing spring, and hotair supply and venting tubes connected with said hot air heating tube.21. The device of claim 19, in which cooling plates are provided forprotecting the coating layer, said cooling plates having holes and beingplaced on said coating layer around the spots to be welded.
 22. Thedevice of claim 20, in which cooling plates are provided for protectingthe coating layer, said cooling plates having holes and being placed onsaid coating layer around the spots to be welded.
 23. A device forresistance welding of insulation-coated sheet metal to at least oneother coated sheet metal, said device comprising two juxtapositionedwelding roller electrodes for roller seam welding, said welding rollerelectrodes comprising two roller discs and interposed between them acutter roller disc adapted to penetrate the coating layers of the metalsheets adjacent the roller electrodes and thus to establish contact ofthe roller electrodes with the blank metal of said sheet metals, meansfor moving at least one of said electrodes toward and away from theother electrode so as to provide a space for placing superposedinsulation-coated sheet metal panels between said electrodes and toestablish contact between said sheet metal panels and said electrodes onmoving the electrodes toward each other, heating means being providedahead of the roller electrodes so as to heat and soften the coatinglayer, cooling means being provided laterally of said roller electrodesto cool the coating layer around the welding seam, a welding currentsource, and connections from said welding current source to saidelectrodes.
 24. The device of claim 23, in which the heating means areorifices blowing hot air upon and thus softening the coating layer aheadof the roller electrodes.